[qntldoql]

Hello, I am currently building a frost model and I wanted to clarify few things. (I have read fluent theory, user and UDF guides and could not find the answers).
First of all, I currently have a species transport set up for the phase 1 (humid air = water vapor + dry air). (phase 2 = ice droplets)
If I only able species transport model, and disable reaction in the materials as well as does not select volumetric reaction + options, etc. Would the equation still be applied? (One with the diffusivity term)

d/dt (rho^q alpha^q y^q) + grad( rho^q alpha^q v_bar^q, y^q) = - grad (alpha^q J^q) + S +R + HR .
(Basically, I want R = HR = 0 and implement the source term S via UDF)


Secondly, how do I apply a UDF source term into the species transport equation. From what I gather, its from Cell zone condition > phase 1 > h20 (for my case). Would it be something else? or is this correct?

Lastly, when designing UDF for a source term.
For example, I have a source term for the momentum equation based on the mass transfer UDF.
S_momentum = -mlg*u_air
where mlg = mass transfer rate.

but the source term UDF is:
DEFINE_SOURCE(S_momentum,c,t,sd,eq)
{
}
From my understanding, C_U(c,t) would be calling for velocity of the entire thread, including ice + humid air.

To only call for the velocity of air, I have used a global parameter
thread* index_air;
and set it equal to the
Thread* air = THREAD_SUB_THREAD(thread, from_phase_index);
from the mass transfer section UDF.
And called the velocity via C_U(c,index_air);
Does this work as how I have intended in FLUENT?


I apologize in for the bombardment of questions and thank you in advance.

[ksunil]

Hi qntldoql,

I am also looking for a similar problem in which moist air and water droplets enter the large domain from the inlet source cells.
could you find a solution to this problem?

Thank you